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| **The accumulation of the worm antigen in the lymphatic vessels. | | **The accumulation of the worm antigen in the lymphatic vessels. |
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| ===Life Cycle of Wuchereria Bancrofti=== | | ===Life cycle of filariasis nematodes=== |
| [[Image:W bancrofti LifeCycle.gif|500 px|center]]
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| Different species of the following genera of [[mosquito]]es are vectors of [[W. bancrofti]] filariasis depending on geographical distribution. Among them are: Culex (C. annulirostris, C. bitaeniorhynchus, C. quinquefasciatus, and C. pipiens); [[Anopheles]] (A. arabinensis, A. bancroftii, A. farauti, A. funestus, A. gambiae, A. koliensis, A. melas, A. merus, A. punctulatus and A. wellcomei); [[Aedes]] (A. aegypti, A. aquasalis, A. bellator, A. cooki, A. darlingi, A. kochi, A. polynesiensis, A. pseudoscutellaris, A. rotumae, A. scapularis, and A. vigilax); Mansonia (M. pseudotitillans, M. uniformis); Coquillettidia (C. juxtamansonia). During a [[blood]] meal, an infected mosquito introduces third-stage filarial larvae onto the [[skin]] of the human host, where they penetrate into the bite wound '''(1)'''. They develop in adults that commonly reside in the [[lymphatic]]s '''(2)''' . The female worms measure 80 to 100 mm in length and 0.24 to 0.30 mm in diameter, while the males measure about 40 mm by .1 mm. Adults produce microfilariae measuring 244 to 296 μm by 7.5 to 10 μm, which are sheathed and have nocturnal periodicity, except the South Pacific microfilariae which have the absence of marked periodicity. The microfilariae migrate into[[lymph]] and blood channels moving actively through [[lymph]] and [[blood]] '''(3)''' . A mosquito ingests the microfilariae during a blood meal '''(4)'''. After [[ingestion]], the microfilariae lose their sheaths and some of them work their way through the wall of the proventriculus and cardiac portion of the mosquito's [[midgut]] and reach the thoracic muscles '''(5)'''. There the microfilariae develop into first-stage larvae '''(6)''' and subsequently into third-stage infective larvae '''(7)'''. The third-stage infective larvae migrate through the [[hemocoel]] to the mosquito's prosbocis '''(8)''' and can infect another human when the [[mosquito]] takes a [[blood]] meal '''(1)'''.
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| ===Life Cycle of Brugia Malayi=== | | {| class="wikitable" |
| [[Image:B malayi LifeCycle.gif|500 px|center]] | | !Type of filariasis |
| | | !Causative nematode |
| The typical vector for [[Brugia malayi]] filariasis are mosquito species from the genera Mansonia and [[Aedes aegypti|Aede]]s. During a blood meal, an infected[[mosquito]] introduces third-stage filarial larvae onto the [[skin]] of the human host, where they penetrate into the bite [[wound]] '''(1)'''. They develop into adults that commonly reside in the [[lymphatic]]s '''(2)'''. The adult [[worm]]s resemble those of [[Wuchereria bancrofti]] but are smaller. Female worms measure 43 to 55 mm in length by 130 to 170 μm in width, and males measure 13 to 23 mm in length by 70 to 80 μm in width. Adults produce microfilariae, measuring 177 to 230 μm in length and 5 to 7 μm in width, which are sheathed and have nocturnal periodicity. The microfilariae migrate into [[lymph]] and enter the[[blood]] stream reaching the peripheral blood '''(3)'''. A [[mosquito]] ingests the microfilariae during a blood meal '''(4)'''. After [[ingestion]], the microfilariae lose their sheaths and work their way through the wall of the proventriculus and cardiac portion of the [[midgut]] to reach the thoracic muscles'''(5)'''. There the microfilariae develop into first-stage larvae '''(6)''' and subsequently into third-stage larvae '''(7)'''. The third-stage larvae migrate through the [[hemocoel]] to the mosquito's prosbocis '''(8)''' and can infect another human when the [[mosquito]] takes a blood meal '''(1)'''.
| | !Vectors |
| ===Life Cycle of Onchocerca volvulus=== | | !Life cycle |
| | | !Illustrative image |
| [[Image:O volvulus LifeCycle.gif|500 px|center]] | | !Comments |
| | | |- |
| During a [[blood]] meal, an infected blackfly (genus Simulium) introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the bite wound '''(1)'''. In [[subcutaneous tissue]]s the larvae '''(2)''' develop into adult filariae, which commonly reside in nodules in subcutaneous connective tissues '''(3)'''. Adults can live in the nodules for approximately 15 years. Some nodules may contain numerous male and female [[worm]]s. Females measure 33 to 50 cm in length and 270 to 400 μm in diameter, while males measure 19 to 42 mm by 130 to 210 μm. In the subcutaneous [[nodule]]s, the female worms are capable of producing microfilariae for approximately 9 years. The microfilariae, measuring 220 to 360 µm by 5 to 9 µm and unsheathed, have a life span that may reach 2 years. They are occasionally found in peripheral [[blood]], [[urine]], and [[sputum]] but are typically found in the [[skin]] and in the [[lymphatic]]s of connective tissues '''(4)'''. A blackfly ingests the microfilariae during a blood meal '''(5)'''. After [[ingestion]], the microfilariae migrate from the blackfly's midgut through the hemocoel to the [[thoracic muscle]]s '''(6)'''. There the microfilariae develop into first-stage larvae '''(7)''' and subsequently into third-stage infective larvae '''(8)''' . The third-stage infective larvae migrate to the blackfly's proboscis '''(9)''' and can infect another human when the fly takes a blood meal '''(1)'''.
| | | rowspan="2" |Lymphatic filariasis |
| ===Life Cycle of Loa loa filaria=== | | |[[Wuchereria bancrofti]] |
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| [[Image:L loa LifeCycle.gif|500 px|center]] | | * Culex as C. pipiens |
| The vector for Loa loa filariasis are flies from two species of the genus Chrysops, C. silacea and C. dimidiata. During a [[blood]] meal, an infected fly (genus Chrysops, day-biting flies) introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the bite [[wound]] '''(1)'''. The larvae develop into adults that commonly reside in [[subcutaneous tissue]] '''(2)'''. The female worms measure 40 to 70 mm in length and 0.5 mm in diameter, while the males measure 30 to 34 mm in length and 0.35 to 0.43 mm in diameter. Adults produce microfilariae measuring 250 to 300 μm by 6 to 8 μm, which are sheathed and have diurnal periodicity. Microfilariae have been recovered from [[spinal fluid]]s, [[urine]], and [[sputum]]. During the day they are found in peripheral blood, but during the noncirculation phase, they are found in the [[lung]]s '''(3)'''. The fly ingests microfilariae during a blood meal '''(4)''' . After ingestion, the microfilariae lose their sheaths and migrate from the fly's [[midgut]] through the [[hemocoel]] to the thoracic muscles of the [[arthropod]]'''(5)'''. There the microfilariae develop into first-stage larvae '''(6)''' and subsequently into third-stage infective larvae '''(7)'''. The third-stage infective larvae migrate to the fly's proboscis '''(8)''' and can infect another human when the fly takes a blood meal '''(1)'''.
| | * Aedes as A. aegypti |
| | | * [[Anopheles]] as A. arabinensis |
| ===Life Cycle of Mansonella Perstans=== | | * Coquillettidia.as C. juxtamansonia |
| [[Image:M perstans LifeCycle.gif|500 px|center]] | | | rowspan="2" | |
| During a blood meal, an infected midge (genus Culicoides) introduces third-stage filarial larvae onto the skin of the [[human]] host, where they penetrate into the bite wound '''(1)''' . They develop into adults that reside in body cavities, most commonly the [[peritoneal cavity]] or [[pleural cavity]], but less frequently in the [[pericardium]] '''(2)''' . The size range for female worms is 70 to 80 mm in length and 120 μm in diameter, and the males measure approximately 45 mm by 60 μm. Adults produce unsheathed and subperiodic microfilariae, measuring 200 by 4.5 μm that reach the blood stream '''(3)''' . A midge ingests microfilariae during a [[blood]] meal '''(4)''' . After [[ingestion]], the microfilariae migrate from the midge's [[midgut]] through the [[hemocoel]] to the thoracic muscles of the [[arthropod]] '''(5)''' . There the microfilariae develop into first-stage larvae '''(6)''' and subsequently into third-stage infective larvae '''(7)''' . The third-stage infective larvae migrate to the midge's proboscis '''(8)''' and can infect another human when the midge takes a blood meal '''(1)''' .
| | * Infected mosquito bite introduces the third stage larva onto the skin and then enters to the blood through the wound. |
| | | * The larvae develop to adult which reside in the '''lymphatic vessels'''. |
| ===Life Cycle of Mansonella Ozzardi===
| | * Adult worm produce sheathed microfiliae that migrate to lymph and blood. They have '''nocturnal periodicity'''. |
| [[Image:M ozzardi LifeCycle.gif|500 px|center]] | | * Another mosquito ingests the microfiliae. |
| During a blood meal, an infected arthropod (midges, genus Culicoides, or blackflies, genus Simulium) introduces third-stage filarial larvae onto the [[skin]] of the [[human]] host, where they penetrate into the bite wound '''(1)''' . They develop into adults that commonly reside in [[subcutaneous tissue]]s '''(2)''' . Adult worms are rarely found in humans. The size range for females worms is 65 to 81 mm in length and 0.21 to 0.25 mm in diameter but unknown for males. Adults worms recovered from experimentally infected Patas monkeys measured 24 to 28 mm in length and 70 to 80 μm in diameter (males) and 32 to 62 mm in length and .130 to .160 mm in diameter (females). Adults produce unsheathed and non-periodic microfilariae that reach the [[blood]] stream '''(3)''' . The arthropod ingests microfilariae during a blood meal '''(4)''' . After [[ingestion]], the microfilariae migrate from the arthropod's [[midgut]] through the [[hemocoel]] to the thoracic muscles '''(5)''' . There the microfilariae develop into first-stage larvae '''(6)''' and subsequently into third-stage infective larvae '''(7)''' . The third-stage infective larvae migrate to arthropod's proboscis '''(8)''' and can infect another human when the arthropod takes a blood meal '''(1)'''
| | * The microfilariae lose their sheaths and work their way through the wall of the proventriculus and cardiac portion of the [[midgut]] to reach the thoracic muscles |
| | | * Microfiliae grow up inside the mosquito till third stage larvae. |
| ===Life Cycle of Mansonella Streptocerca===
| | * In another bite to a host skin the mosquito introduces the larvae onto the skin. |
| [[Image:M streptocerca LifeCycle.gif|500 px|center]]
| | | rowspan="2" |[[Image:W bancrofti LifeCycle.gif|350 px|center]] |
| During a [[blood]] meal, an infected midge (genus Culicoides) introduces third-stage filarial larvae onto the [[skin]] of the [[human]] host, where they penetrate into the bite wound '''(1)''' . They develop into adults that reside in the [[dermis]], most commonly less than 1 mm from the [[skin]] surface '''(2)''' . The females measure approximately 27 mm in length. Their diameter is 50 μm at the level of the [[vulva]] (anteriorly) and [[ovaries]] (near the posterior end), and up to 85 μm at the mid-body. Males measure 50 μm in diameter. Adults produce unsheathed and non-periodic microfilariae, measuring 180 to 240 μm by 3 to 5 μm, which reside in the skin but can also reach the peripheral [[blood]] '''(3)''' . A midge ingests the microfilariae during a blood meal '''(4)''' . After [[ingestion]], the microfilariae migrate from the midge's [[midgut]] through the [[hemocoel]] to the thoracic muscles '''(5)''' . There the microfilariae develop into first-stage larvae '''(6)''' and subsequently into third-stage larvae '''(7)''' . The third-stage larvae migrate to the midge's proboscis '''(8)''' and can infect another human when the midge takes another blood meal'''(1)''' .
| | | rowspan="2" | |
| | * The difference between the nematodes causing lymphatic filariasis is in the shape and size of the worm. |
| | * The Brugia worms are similar to the W. bancrofti but smaller. |
| | |- |
| | |[[Brugia timori]] and [[Brugia malayi]] |
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| | * Mansonia |
| | * Aedes |
| | |- |
| | | rowspan="4" |Subcutaneous filariasis |
| | |[[Loa loa filaria]] |
| | | |
| | * Chrysops |
| | * C. silacea |
| | * C. dimidiata |
| | | rowspan="4" | |
| | * Infected fly bite introduces the third stage larva onto the skin and then enters to the blood through the wound. |
| | * The larvae develop to adult which reside in the '''subcutaneous tissue'''. |
| | * Loa Loa adult worm produce sheathed microfilariae that are found in the blood during day and in the lungs during the non circulating phase. They have '''diurnal periodicity'''. |
| | * Another fly ingests the microfiliae. |
| | * After ingestion, the microfilariae lose their sheaths and migrate from the fly's [[midgut]] through the [[hemocoel]] to the thoracic muscles of the [[arthropod]]. |
| | * Microfiliae grow up inside the fly till third stage larvae. |
| | * The third-stage infective larvae migrate to the fly's proboscis and in another bite the cycle restarts. |
| | | rowspan="4" |[[Image:L loa LifeCycle.gif|350 px|center]] |
| | | rowspan="4" | |
| | * Unlike Loa Loa filaria, Mansonella streptocerca , Mansonella ozzardi and Onchocerca volvolus produce '''unsheathed non-periodic microfilariae'''. |
| | * Mansonela streptocerca adults residue in the dermis. |
| | * Onchocerca volvulus adults residue mainly in the subcutaneous nodules. Their microfilariae can be found in the peripheral [[blood]], [[urine]], and [[sputum]] but are typically found in the [[skin]] and in the [[Lymphatic|lymphatics]] of connective tissue. |
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| | |[[Mansonella streptocerca]] |
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| | * Midge (genus Culicoides) |
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| | |[[Mansonella ozzardi]] |
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| | * Midge (genus Culicoides) |
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| | |[[Onchocerca volvulus]] |
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| | * Blackfly (genus Simulium) |
| | |- |
| | |Serous cavity filariasis |
| | |[[Mansonella perstans]] |
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| | * Midge (genus Culicoides) |
| | * Blackfly (genus Simulium) |
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| | * Infected midge bite introduces the third stage larva onto the skin and then enters to the blood through the wound. |
| | * The larvae develop to adult which reside in the different body cavities like [[peritoneal cavity]], [[pleural cavity]], and less frequently in the [[pericardium]]. |
| | * Adult worm produce unsheathed subperiodic microfilariae that reaches the blood stream. |
| | * Another midge ingests microfilariae during a [[blood]] meal. |
| | * After [[ingestion]], the microfilariae migrate from the midge's [[midgut]] through the [[hemocoel]] to the thoracic muscles of the [[arthropod]]. |
| | * Microfiliae grow up inside the midge till third stage larvae. |
| | * The third-stage infective larvae migrate to the midge's proboscis and in another bite the cycle restarts. |
| | |[[Image:M perstans LifeCycle.gif|350 px|center]] |
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| | |} |
| | Life cycles of the roundworms causing filariasis: |
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| ==References== | | ==References== |
